The excimer-forming fluorophore dipyrenylpropane has been used to meas
ure the relative fluidity of total membranes isolated from Escherichia
coil grown at 30 or 45 degrees C, or exposed to a heat-shock from 30
to 45 degrees C for various periods of time. Parallel experiments were
performed using [S-35]methionine pulse-labeling of cells, to study th
e induction of heat-shock proteins (HSPs) at different times after the
sudden change in E. coli growth-temperature from 30 to 45 degrees C.
Results suggest that upon an abrupt temperature upshift from 30 to 35
degrees C, membrane fluidity adjustment to the steady-state level at t
he high temperature, takes place during the E. coli heat-shock respons
e.